The quality of service (QoS) for wireless communication needs to be improved. Measurements for the QoS include average service rate, packet loss and error rate, packet delay bound . . . etc. The average service rate means the average transmitting rate of the communication data in the communication sessions. The packet loss and error rate means the maximum allowable error rate of the communication data in the communication sessions by bits. The packet delay bound means the maximum allowable time of communication data in communication sessions based on the PDUs.
For wireless communication, data in the communication session, also called PDUs, are transmitted in a packet form in a fixed bandwidth or band frequency. The QoS depends on how to allocate the data of communication sessions from each mobile communication devices in a limited bandwidth. For example, the QoS can be adjusted by reducing the transmission energy but keeping the energy above the requirement. Adjusting energy is a common way to allocate resources.
In a CDMA communication system, the interference has greater influence on the signal than the noise does. Therefore, the signal-to-interference rate (SIR) is used as a measurement for QoS in a CDMA communication system. For providing more communication session in a limited bandwidth, the best situation is to have the minimum SIR for each data of the communication session. The minimum SIR can guarantee the acceptable packet loss and error rate.
The power-strengths of each communication sessions are different depending on positioning of the mobile communication devices and packet error rate. The quality of service can be enhanced by increasing the power-strength or decreasing the service rate of some communication sessions. However, increasing the power-strength of the communication session may lead to additional interference to other communication sessions. Also, decreasing in service rate may delay the communication session for the mobile communication device.
Considering the loading of the base station, it is commonly to use time-based or power-based solutions to arrange and schedule the transmit of PDUs. The time-based scheduler or power-based scheduler according to the prior art has the conception of scheduling but lacks proper allocation. For example, a general time-based scheduler schedules according to the orders and the required QoS of the communication session, and has nothing to do with power resources allocation. A general power-based scheduler adjusts the power of communication session for a fixed QoS. This means that the prior art only deals the problem of constant bit rate (CBR), not the variable bit rate (VBR).
However, the present invention provides a system or method for classifying the power-strength for communication sessions to schedule and transmit based on the priority sequence in the downlink direction from base stations to mobile communication devices in wireless communication system. This invention is suitable to the systems of CBR and VBR for solving the problem of the prior art.